This invention relates to the field of air cleaners, and more particularly to an improved filter for use to improve a known system for cleaning the air admitted to diesel locomotive engines. The system comprises a housing having an outlet for connection to the engine inlet, and a panel with a plurality of rectangular inlet openings, into which bag-shaped "cartridges" of glass-fiber filter fabric are inserted, being secured by clamping an out-turned lips of the bags to the face of the housing. The clamping member includes an open wire skeleton frame or cage for holding the walls of the bag apart to give a maximized working surface and to protect against turbo-surge. The fabric is coated witn an oil adhesive to assist in trapping particulate matter.
While this system has been quite successful, the filter medium is initially of relatively low efficiency, and its efficiency decreases further as the oil adhesive takes up air contaminants. The necessity for the internal cage means that the system must be installed with sufficient space around it to permit removal and replacement of this element, and also results in wear on the inner surface of the bag.